Shortcut for operator context panel (redo panel) in 2.8?
Yes! Just press F9 or go to Edit > Adjust Last Operation, which displays the Redo Panel a.k.a. Operator Panel as a simple pop-up window after using any operator:



Quoting from the Manual: 


  After an operation is complete you can tweak the parameters of the operation afterwards. In editors that support it, there is a “head-up display” panel in the bottom left based on the last performed operation; dependent on mode and context. Alternatively, you can create a pop-up with F9 which does the same thing.